[KPhotoAlbum] Cycles in member maps

[Tuomas Suutari]

On 2007-04-04 Wednesday 17:41, Tero Tilus wrote:
> 2007-04-04 16:02, Tuomas Suutari:
> > I've been thinking to deny cycles in KPhotoAlbum's member maps.
>
> Very good idea.
>
> Thinking a little...  It looks like the underlying concept of these
> "member maps" is set theory and "A is member of B" is to say A is a
> subset of B (yes, subset, not member).

Yep, that's a good analogy. And it works fine also when some item 
belongs to two or more membergroups.

For example:
D < B,  B < A,  D < C,  C < A
(Using following notation: X < Y means X is a subset of Y)

Or same as a graph:
     /-> B -\
 A -|        |-> D
     \-> C -/

Those could be useful and I see no reason to deny them. (Think for 
example: A="People" B="Friend" C="Customer" D="John Smith".)


> > Can you think any (even remotely) good reason to have cycles in
> > member maps
>
> How about cities as tags and the member map relations representing
> poblic transport connections?  Or companies as tags and their mutual
> ownerships as relations.  I really do not know who would need
> those. ;) However, you can store and represent meaningfull data that
> way.

I've thought those, but as a separate concept to keep meaning of the 
member groups more clear. General relations like those could be useful, 
but I have no time to implement those yet. Let's talk more about it 
after the SQL backend is released.


> > or would anyone be happy if those weren't allowed?
>
> Did you mean UNhappy?

Yeah, there's a typo. I meant "...or would everyone be happy..." :)

-- 
Tuomas Suutari | +358 50 3806983 | thsuut at utu.fi